n=int(input())
s = input()
Ra = s.count('R')
t = s[:Ra]
Rb = t.count('R')
print(Ra-Rb) n=int(input()) n int(input()) int input() input s = input() s input() input Ra = s.count('R') Ra s.count('R') s.count s count 'R' t = s[:Ra] t s[:Ra] s :Ra Ra Rb = t.count('R') Rb t.count('R') t.count t count 'R' print(Ra-Rb) print Ra-Rb Ra Rb n=int(input()) int(input()) n Rb = t.count('R') t.count('R') Rb s = input() input() s Ra = s.count('R') s.count('R') Ra t = s[:Ra] s[:Ra] t
n=int(input())
s = input()
Ra = s.count('R')
t = s[:Ra]
Rb = t.count('R')
print(Ra-Rb)